The spaceflight consisted of one orbit around Earth, the shortest manned orbital flight to date. According to official records, the spaceflight took 108 minutes from launch to landing. As planned, Gagarin parachuted to the ground separately from his spacecraft after ejecting at 7 km (23,000 ft) altitude. Due to the secrecy surrounding the Soviet space program at the time, many details of the spaceflight only came to light years later, and several details in the original press releases turned out to be false.

The world's first artificial satellite, Sputnik 1, had been put into orbit by the Soviet Union in 1957. This event could be considered the beginning of the Space Race between the Soviet Union and the United States, the two Cold War superpowers. Both countries wanted to develop their spaceflight technology quickly, and in particular, both wanted to be the first to launch a successful human spaceflight. The Soviet programme for doing this was the Vostok programme. Prior to a manned spaceflight, the Soviets launched several precursor unmanned missions between May 1960 and March 1961, to test and develop the Vostok rocket and Vostok spacecraft technology. These missions had varied success, but the final two unmanned missions—Korabl-Sputnik 4 and Korabl-Sputnik 5—were outright successes, opening the door for a manned flight.

The Vostok spacecraft was designed to carry a single cosmonaut. Yuri Gagarin, 27, was chosen as the prime pilot of Vostok 1, with Gherman Titov and Grigori Nelyubov as backups. These assignments were formally made on April 8, four days before the mission, but Gagarin had been a favourite among the cosmonaut candidates for at least several months.[7]:262,272

The final decision of who would fly the mission relied heavily on the opinion of Nikolai Kamanin. In an April 5 diary entry, Kamanin wrote that he was still undecided between Gagarin and Titov.[8] He wrote: "The only thing that keeps me from picking [Titov] is the need to have the stronger person for the one day flight."[9] Kamanin was referring to the second mission, Vostok 2, which would last a full day, compared to the relatively short single-orbit mission of Vostok 1. When Gagarin and Titov were informed of the decision during a meeting on April 9, Gagarin was very happy, and Titov was disappointed.[10] On April 10, this meeting was reenacted in front of television cameras, so there would be official footage of the event. This included an acceptance speech by Gagarin.[11] As an indication of the level of secrecy involved, one of the other cosmonaut candidates, Alexey Leonov, later recalled that he did not know who was chosen for the mission until after the spaceflight had begun.[12]

Gagarin was examined by a team of doctors prior to his flight. One doctor gave her recollection of the events in an interview with RT in April 2011: "Gagarin looked more pale than usual. He was unsociable and quiet, which was not like him at all. He would answer by nodding or a short 'yes' to all questions. Sometimes he would start humming some tunes. This was a different Gagarin. We geared him up, and hugged. And I said, "Yuri, everything will be fine." And he nodded back."[13]

Unlike later Vostok missions, there were no dedicated tracking ships available to receive signals from the spacecraft. Instead they relied on the network of ground stations, also called Command Points, to communicate with the spacecraft; all of these Command Points were located within the Soviet Union.[14]

Because of weight constraints, there was no backup retrorocket engine. The spacecraft carried 10 days of provisions to allow for survival and natural decay of the orbit in the event the retrorockets failed.

The entire mission would be controlled by either automatic systems, or by ground control. This was because medical staff and spacecraft engineers were unsure how a human might react to weightlessness, and therefore it was decided to lock the pilot's manual controls. In an unusual move, a code to unlock the controls was placed in an onboard envelope, for Gagarin's use in case of emergency.[7]:278 But prior to the flight, Kamanin and others told Gagarin the code anyway.[15][16]

On Baikonur cosmodrome on the morning of April 11, 1961, the Vostok-K rocket, together with the attached Vostok 3KA spacecraft, were transported several miles to the launch pad, in a horizontal position. Once they arrived at the launch pad, Sergei Korolev inspected the rocket and spacecraft for problems, and without finding any, the rocket was raised into the upright position.[17] At 10 am (Moscow Time), Gagarin and Titov were given a final review of the flight plan.[17] They were informed that launch was scheduled to occur the following day, at 9:07 am Moscow Time. This time was chosen so that when the spacecraft started to fly over Africa, which was when the retrorockets would need to fire for reentry, the solar illumination would be ideal for the orientation system's sensors.[18]

At 6 pm, once various physiological readings had been taken, the doctors instructed the cosmonauts not to discuss the upcoming missions. That evening Gagarin and Titov relaxed by listening to music, playing pool, and chatting about their childhoods.[12] At 9:50 pm, both men were offered sleeping pills, to ensure a good night's sleep, but they both declined.[19] Physicians had attached sensors to the cosmonauts, to monitor their condition throughout the night, and they believed that both had slept well.[20] Gagarin's biographers Doran and Bizony say that neither Gagarin nor Titov slept that night.[21] Korolev didn't sleep that night, due to anxiety caused by the imminent spaceflight.[18]

At 5:30 am Moscow time, on the morning of April 12, 1961, both Gagarin and his backup Titov were woken.[22] They were given breakfast, assisted into their spacesuits, and then were transported to the launch pad.[23] Gagarin entered the Vostok 1 spacecraft, and at 7:10 am local time (04:10 UT), the radio communication system was turned on.[23] Once Gagarin was in the Vostok 1 spacecraft, his picture appeared on television screens in the launch control room from an onboard camera. Launch would not occur for another two hours, and during the time Gagarin chatted with the mission's main CapCom, as well as Chief Designer Sergei Korolev, Nikolai Kamanin, and a few others.[23] Following a series of tests and checks, about forty minutes after Gagarin entered the spacecraft, its hatch was closed. Gagarin, however, complained that the hatch was not sealed properly, and technicians spent nearly an hour removing all the screws and sealing the hatch again.[2] According to a recent obituary, Vostok's chief designer, Oleg Ivanovsky, personally helped rebolt the hatch.[24] There is some disagreement over whether the hatch was, in fact, not sealed correctly as a more recent account stated the indication was false.

During this time Gagarin requested some music to be played over the radio.[25]Sergei Korolev was very nervous in the lead up to the launch; he experienced chest pains, and took a pill to calm his heart.[26] Gagarin, on the other hand, was described as calm; about half an hour before launch his pulse was recorded at 64 beats per minute.[27]

06:09 UT Two minutes into the flight and the four strap-on booster sections of the Vostok rocket have used up the last of their propellant; they shut down and drop away from the core vehicle. (T+ 119 s)

06:12 UT Five minutes into the flight and the Vostok rocket core stage has used up its propellant, shuts down and falls away from the Vostok spacecraft and final rocket stage. The final rocket stage ignites to continue the journey to orbit. (T+ 300 s)

06:13 UT The rocket is still firing, pushing Vostok 1 toward orbit. Gagarin reports, "...the flight is continuing well. I can see the Earth. The visibility is good.... I almost see everything. There's a certain amount of space under cumulus cloud cover. I continue the flight, everything is good."

Yuri Gagarin in Vostok 1

06:14 UT The rocket continues to fire, starting to pass over central Russia. Gagarin reports, "Everything is working very well. All systems are working. Let's keep going!"

06:15 UT Three minutes into the burn of the final rocket stage and Gagarin reports, "Zarya-1, Zarya-1, I can't hear you very well. I feel fine. I'm in good spirits. I'm continuing the flight..." Vostok 1 is moving further downrange from the Baikonur Cosmodrome. He is reporting back to Zarya-1 (the Baikonur ground station) and must be starting to move out of radio range of that station.

Ground controllers did not know if a stable orbit had been achieved until 25 minutes after launch.

06:17 UT The Vostok rocket final stage shuts down, ten seconds later the spacecraft separates and Vostok 1 reaches orbit. (T+ 676 s) Gagarin reports, "The craft is operating normally. I can see Earth in the view port of the Vzor. Everything is proceeding as planned". Vostok 1 passes over the Soviet Union and moves on over Siberia.

Part of the Vostok 1 control panel

06:21 UT Vostok 1 passes over the Kamchatka peninsula and out over the North Pacific Ocean. Gagarin radios, "...the lights are on on the descent mode monitor. I'm feeling fine, and I'm in good spirits. Cockpit parameters: pressure 1; humidity 65; temperature 20; pressure in the compartment 1; first automatic 155; second automatic 155; pressure in the retro-rocket system 320 atmospheres...."

06:25 UT As Vostok 1 begins its diagonal crossing of the Pacific Ocean from Kamchatka peninsula to the southern tip of South America, Gagarin asks, "What can you tell me about the flight? What can you tell me?". He is requesting information about his orbital parameters. The ground station at Khabarovsk reports back, "There are no instructions from No. 20 (Sergey Korolyov), and the flight is proceeding normally" They are telling Gagarin that they don't have his orbital parameters yet because the spacecraft has been in orbit for only 6 minutes, but the spacecraft systems are performing well.

06:31 UT Gagarin transmits to the Khabarovsk ground station, "I feel splendid, very well, very well, very well. Give me some results on the flight!". Vostok 1 is nearing the VHF radio horizon for Khabarovsk and they respond, "Repeat. I can't hear you very well". Gagarin transmits again, "I feel very good. Give me your data on the flight!" Vostok 1 passes out of VHF range of the Khabarovsk ground station and contact is lost.

06:37 UT Vostok 1 continues on its journey as the Sun sets over the North Pacific. Gagarin crosses into night, northwest of the Hawaiian Islands. Out of VHF range with ground stations, communications must now take place via HF radio.

06:46 UT Khabarovsk ground station sends the message "KK" via telegraph (on HF radio to Vostok 1). This message means, "Report the monitoring of commands." They were asking Gagarin to report when the spacecraft automated descent system had received its instructions from the ground control. Gagarin reported back at 06:48 UT.

06:48 UT Vostok 1 crosses the equator at about 170° West, traveling in a south east direction and begins crossing the South Pacific. Gagarin transmits over HF radio, "I am transmitting the regular report message: 9 hours 48 minutes (Moscow Time), the flight is proceeding successfully. Spusk-1 is operating normally. The mobile index of the descent mode monitor is moving. Pressure in the cockpit is 1; humidity 65; temperature 20; pressure in the compartment 1.2 ... Manual 150; First automatic 155; second automatic 155; retro rocket system tanks 320 atmospheres. I feel fine...."

06:49 UT Gagarin reports he is on the night side of the Earth.

06:51 UT Gagarin reports the sun-seeking attitude control system has been switched on. The sun-seeking attitude control system is used to orient Vostok 1 for retrofire. The automated orientation system consisted of two redundant systems: an automatic/solar orientation system and a manual/visual orientation system. Either system could operate the two redundant cold nitrogen gas thruster systems, each with 10 kg (22 lb) of gas.

06:53 UT The Khabarovsk ground station sends Gagarin the following message via HF radio, "By order of No.33 (General Nikolai Kamanin) the transmitters have been switched on, and we are transmitting this: the flight is proceeding as planned and the orbit is as calculated." They tell Gagarin that Vostok 1 is in a stable orbit. He acknowledges the message.

06:57 UT Vostok 1 is over the South Pacific between New Zealand and Chile when Gagarin sends this message, "...I'm continuing the flight, and I'm over America. I transmitted the telegraph signal "ON".

07:00 UT Vostok 1 crosses the Strait of Magellan at the tip of South America. News of the Vostok 1 mission is broadcast on Radio Moscow.[29]

Path of Gagarin's complete orbit; the landing point is west of the takeoff point because of the eastward rotation of the Earth.

07:04 UT Gagarin sends spacecraft status message, similar to the one sent at 06:48. The message is not received by ground stations.

07:09 UT Gagarin sends spacecraft status message, the message is not received by ground stations.

07:10 UT Passing over the South Atlantic, the Sun rises and Vostok 1 is in daylight again. Vostok 1 is 15 minutes from retrofire.

07:13 UT Gagarin sends spacecraft status message, similar to the one sent at 06:48. Moscow picks up this partial message from Gagarin, "I read you well. The flight is going...."

07:18 UT Gagarin sends spacecraft status message, the message is not received by ground stations.

07:23 UT Gagarin sends spacecraft status message, the message is not received by ground stations.

The automatic system brought Vostok 1 into alignment for retrofire about 1-hour into the flight.

At 07:25 UT, the spacecraft's automatic systems brought it into the required attitude (orientation) for the reentry engine firing, and shortly afterwards, the engine firing occurred, also known as retrofire. This took place over the west coast of Africa, near Angola, about 8,000 km (5,000 mi) from the desired landing point. The liquid-fueled retrorockets fired for about 42 seconds.

Ten seconds after retrofire, commands were sent to separate the Vostok service module from the reentry module (sharik), but the Vostok equipment module unexpectedly remained attached to the reentry module by a bundle of wires. At around 07:35 UT, the two halves of the spacecraft begin reentry and went through strong gyrations as Vostok 1 neared Egypt. At this point the wires broke, the two modules separated, and the descent module settled into the proper reentry attitude. Gagarin telegraphed "Everything is OK" despite continuing gyrations; he later reported that he did not want to "make noise" as he had (correctly) reasoned that the gyrations did not endanger the mission (and were apparently caused by the spherical shape of the reentry module).

As Gagarin continued his descent, he experienced about 8 g (Gagarin's own report states "over 10 g") during reentry but remained conscious.

In case of reentry engine malfunction, the spacecraft was designed to descend within 10 days due to orbital decay. However, the actual orbit differed from the planned and would not have allowed descent until 20 days postlaunch while the life support system was designed to function for only 10 days.[30]

At 07:55 UT, when Vostok 1 was still 7 km from the ground, the hatch of the spacecraft was released, and two seconds later Gagarin was ejected. At 2.5 km (8,200 ft) altitude, the main parachute was deployed from the Vostok spacecraft. Two schoolgirls witnessed the Vostok landing and described the scene: "It was a huge ball, about two or three metres high. It fell, then it bounced and then it fell again. There was a huge hole where it hit the first time."

A farmer and her daughter observed the strange scene of a figure in a bright orange suit with a large white helmet landing near them by parachute. Gagarin later recalled, "When they saw me in my space suit and the parachute dragging alongside as I walked, they started to back away in fear. I told them, don't be afraid, I am a Soviet citizen like you, who has descended from space and I must find a telephone to call Moscow!"

Gagarin's flight was announced on the Soviet radio by Yuri Levitan, the same speaker, who announced all major events in the Great Patriotic War. As with all previous and subsequent Soviet rocket launches, the flight preparation was kept secret and the news were aired only post-factum. The flight was celebrated as a great triumph of the Soviet science and technology demonstrating the superiority of the socialist system over capitalism. Moscow and other cities in the USSR held mass demonstrations, the scale of which was comparable to World War II Victory Parades. Gagarin was awarded the title of Hero of the Soviet Union, the nation's highest honour. He also became an international celebrity with numerous honours and awards.[31]

April 12 was declared Cosmonautics Day in the USSR, and is celebrated today in Russia as one of the official "Commemorative Dates of Russia."[32] In 2011, it was declared the International Day of Human Space Flight by the United Nations.[33]

Gagarin's informal reply poyekhali! became a historical phrase used to refer to the arrival of the Space Age in human history.[34] Later it was included in the refrain of a Soviet patriotic song written by Alexandra Pakhmutova and Nikolai Dobronravov (He said "let's go!" He waved his hand).[35]

The Soviet press later reported that minutes before boarding the spacecraft Gagarin made a speech: "Dear friends, you who are close to me, and you whom I do not know, fellow Russians, and people of all countries and all continents: in a few minutes a powerful space vehicle will carry me into the distant realm of space. What can I tell you in these last minutes before the launch? My whole life appears to me as one beautiful moment. All that I previously lived through and did, was lived through and done for the sake of this moment." He actually recorded the speech—"a stream of banalities prepared by anonymous speechwriters", according to historian Asif Siddiqi—in Moscow.[7]:274

Officially, the U.S. congratulated the Soviet Union on its accomplishments.[36]

Writing for the New York Times shortly after the flight, however, journalist Arthur Krock described mixed feelings in the United States due to fears of the spaceflight's potential military implications for the Cold War,[37] and the Detroit Free Press wrote that "the people of Washington, London, Paris and all points between might have been dancing in the streets" if it were not for "doubts and suspicions" about Soviet intentions.[38] Other US writers reported worries that the spaceflight had won a propaganda victory on behalf of communism.[39][40] President John F. Kennedy was quoted as saying that it would be "some time" before the US could match the Soviet launch vehicle technology, and that "the news will be worse before it's better."[39] Kennedy also sent congratulations to the Soviet Union for their "outstanding technical achievement."[39] Opinion pages of many US newspapers urged renewed efforts to overtake the Soviet scientific accomplishments.[38]

Adlai Stevenson, then the US ambassador to the United Nations, was quoted as saying, "Now that the Soviet scientists have put a man into space and brought him back alive, I hope they will also help to bring the United Nations back alive,"[38] and on a more serious note urged international agreements covering the use of space[38] (which did not occur until the Outer Space Treaty of 1967).

Prime Minister Jawaharlal Nehru of India praised the Soviets for "a great victory of man over the forces of nature"[39] and urged that it be "considered as a victory for peace."[38]The Economist voiced worries that orbital platforms might be used for surprise nuclear attacks.[38] The Svenska Dagbladet in Sweden chided "free countries" for "splitting up and frittering away" their resources,[38] while West Germany's Die Welt argued that America had the resources to have sent a man into space first but was beaten by Soviet purposefulness.[38] Japan's Yomiuri Shimbun urged "that both the United States and the Soviet Union should use their new knowledge and techniques for the good of mankind,"[38] and Egypt's Akhbar El Yom likewise expressed hopes that the cold war would "turn into a peaceful race in infinite space" and turn away from armed conflicts such as the Laotian Civil War.[38]

The FAI rules in 1961 required that a pilot must land with the spacecraft to be considered an official spaceflight for the FAI record books.[7]:283 Although some contemporary Soviet sources stated that Gagarin had parachuted separately to the ground,[41] the Soviet Union officially insisted that he had landed with the Vostok; the government forced the cosmonaut to lie in press conferences, and the FAI certified the flight. The Soviet Union did not admit until 1971 that Gagarin had ejected and landed separately from the Vostok descent module.[7]:283

Four decades after the flight, historian Asif Siddiqi wrote that Vostok 1

will undoubtedly remain one of the major milestones in not only the history of space exploration, but also the history of the human race itself. The fact that this accomplishment was successfully carried out by the Soviet Union, a country completely devastated by war just sixteen years prior, makes the achievement even more impressive. Unlike the United States, the USSR had to begin from a position of tremendous disadvantage. Its industrial infrastructure had been ruined, and its technological capabilities were outdated at best. A good portion of its land had been devastated by war, and it had lost about 25 million citizens ... but it was the totalitarian state that overwhelmingly took the lead [in the space race].[7]:282

The landing site is now a monument park. The central feature in the park is a 25 meter tall monument that consists of a silver metallic rocketship rising on a curved metallic column of flame, from a wedge shaped, white stone base. In front of this is a 3 meter tall, white stone statue of Yuri Gagarin, wearing a spacesuit, with one arm raised in greeting and the other holding a space helmet.[42][43][44]

Vostok, the lead ship of Faddey Bellingshausen, who discovered Antarctica during the Russian expedition to the south polar region in 1819/20. Some sources connect the name Vostok 1 to Bellingshausen's ship.[46]

^Burgess and Hall, p.151. During a post-flight press conference on April 15, Alexander Nesmeyanov claimed that Gagarin took a sleeping pill. Also, Siddiqi, p.273, claims that they were both asleep at 9:30 pm when Korolev came to visit them, but Burgess and Hall, p.151, says Korolev spoke with them at this time.

^Siddiqi, p.273; In a post-flight press conference, Gagarin also stated that he slept well.

^Arthur Krock, "In The Nation; Concentration of Science on Outer Space," New York Times p. 28, April 14, 1961. "But because of the distrust that now exists among the great nations, and has plunged them into huge programs of deadly rearmament, an achievement by one which carries a clear and direct potential of military supremacy engenders fear of its use.... And so it has become as impossible for either of the groups divided by the Cold War to welcome unreservedly such feats as Major Gagarin's in the opposite camp."

^ abcdefghij"Opinion of the Week: At Home and Abroad," New York Times p. E11 (April 16, 1961). Quotes of reactions from many US and international sources.